Essential Go for, while loops  Suggest an edit

Different forms of for loop

Simple form using one variable:

for i := 0; i < 10; i++ {
    fmt.Print(i, " ")
}

Using two variables (or more):

for i, j := 0, 0; i < 5 && j < 10; i, j = i+1, j+2 {
    fmt.Println(i, j)
}

Without using initialization statement:

i := 0
for ; i < 10; i++ {
    fmt.Print(i, " ")
}

Without a test expression:

for i := 1; ; i++ {
    if i&1 == 1 {
        continue
    }
    if i == 22 {
        break
    }
    fmt.Print(i, " ")
}

Without increment expression:

for i := 0; i < 10; {
    fmt.Print(i, " ")
    i++
}

When all three initialization, test and increment expressions are removed, the loop becomes infinite:

i := 0
for {
    fmt.Print(i, " ")
    i++
    if i == 10 {
        break
    }
}

This is an example of infinite loop with counter initialized with zero:

for i := 0; ; {
    fmt.Print(i, " ")
    if i == 9 {
        break
    }
    i++
}

When just the test expression is used (acts like a typical while loop):

i := 0
for i < 10 {
    fmt.Print(i, " ")
    i++
}

Using just increment expression:

i := 0
for ; ; i++ {
    fmt.Print(i, " ")
    if i == 9 {
        break
    }
}

Iterate over a range of values using index and value:

ary := [5]int{0, 1, 2, 3, 4}
for index, value := range ary {
    fmt.Println("ary[", index, "] =", value)
}

Iterate over a range using just index:

for index := range ary {
    fmt.Println("ary[", index, "] =", ary[index])
}

Iterate over a range using just index:

for index, _ := range ary {
    fmt.Println("ary[", index, "] =", ary[index])
}

Iterate over a range using just value:

for _, value := range ary {
    fmt.Print(value, " ")
}

Iterate over a range using key and value for map (may not be in order):

mp := map[string]int{"One": 1, "Two": 2, "Three": 3}
for key, value := range mp {
    fmt.Println("map[", key, "] =", value)
}

Iterate over a range using just key for map (may be not in order):

for key := range mp {
    fmt.Print(key, " ") //One Two Three
}

Iterate over a range using just key for map (may be not in order):

for key, _ := range mp {
    fmt.Print(key, " ") //One Two Three
}

Iterate over a range using just value for map (may be not in order):

for _, value := range mp {
    fmt.Print(value, " ") //2 3 1
}

Iterate over a range for channels (exits if the channel is closed):

ch := make(chan int, 10)
for i := 0; i < 10; i++ {
    ch <- i
}
close(ch)

for i := range ch {
    fmt.Print(i, " ")
}

Iterate over a range for string (gives Unicode code points):

utf8str := "B = \u00b5H" //B = ┬ÁH
for _, r := range utf8str {
    fmt.Print(r, " ") //66 32 61 32 181 72
}
fmt.Println()
for _, v := range []byte(utf8str) {
    fmt.Print(v, " ") //66 32 61 32 194 181 72
}
fmt.Println(len(utf8str)) //7

as you see utf8str has 6 runes (Unicode code points) and 7 bytes.

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